Another vote for the Topeak. I have the medium. I usually carry:
- Tube (700cx23-28)
- Pedro's Tire Levers
- Patch Kit
- Multi-tool with chain tool
- Energy bar
- Spare cash
- Keys
- Digital camera or eight spare AA batteries
I can cram my wallet in there too if I unzip the expanding section.
I also slide my glasses case into the elastic straps underneath. Great for having both pairs at twilight or if I'll have to read something at my destination.
My favorite feature is that you can order extra QR mounts separately. (Have your LBS look in the QBP catalog.) I have one bag and two extra QR mounts so I can swap it between the three bikes. It's a lot easier and cheaper to keep one bag stocked instead of several.